Mayo Clinic Laboratories > Genetics > Pharmacogenomics > Frequently asked questions

Frequently asked questions

Frequently asked questions, and answers, about pharmacogenomics testing

From clarifying which drugs are included in our PGx testing, what specimen type is preferred, and who to contact for more information, we’ve provided answers to facilitate test ordering.

What are the benefits of the Focused Pharmacogenomics Panel, PGXQP?

PGXQP tests only specific variants within genes with high evidence of drug-gene information.

  • This panel targets CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP3A4, CYP3A5, CYP4F2,SLCO1B1, VKORC1, and the rs12777823 variant.
    • The test report is formatted as a list of more than 85 commonly prescribed drugs and potential correlations based on the patient’s genotype. View a sample report.
  • NOTE: If testing for one drug or one gene, a single gene or smaller pharmacogenomic test may occasionally be more appropriate (e.g., CYP2C19 for clopidogrel).

What are the benefits of the Psychotropic Pharmacogenomics Gene Panel, PSYQP?

  • This panel includes targeted testing for specific variants within ADRA2A, ANKK1, CHRNA3, COMT, CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP3A4, CYP3A5, DRD2, EPHX1, GRIK4, HLA-A*31:01, HLA-B*15:02, HTR2A, HTR2C, MTHFR, OPRM1, SCN1A, SLC6A4 (5-HTT), and UGT2B15.
  • This panel includes drugs with high-level evidence for drug-gene interactions, as well as those with emerging evidence based on published literature. The report aims for transparency, with a special comment highlighting information on drug-gene interactions with emerging evidence.  
  • Results reports are formatted similarly to PGXQP but restricted to psychotropic drugs and organized by categories (e.g., antidepressants, antipsychotics, etc.). View a sample report.

NOTE: If testing for one drug or one gene, a single gene or smaller pharmacogenomic test may occasionally be more appropriate (e.g., CYP2D6 for atomoxetine).

Who can I contact if I have questions on which test to order or understanding the results?

Our dedicated team of genetic counselors, pharmacists, pathologists, and laboratory geneticists is ready to help. Please contact Mayo Lab Inquiry (MLI) at 800-533-1710 for more information.

Where can I find more information on a specific drug?

To learn about medications included in our PGXQP and PSYQP panels, clients can search our online test catalog and open the sample report PDF to view the drugs included in the report.

Because pharmacogenomic results must be used in the context of a patient’s overall health, including other medications and co-morbidities, reports cannot provide exact dosing guidelines. View our Pharmacogenomic Association Tables to access publicly available information about drugs and pharmacogenomically relevant genes, including the FDA Table of Pharmacogenomic Associations, FDA drug labels, and gene-drug pairs from CPIC.

Why isn’t a drug included in the report?

We only include recommendations consistent with FDA labels or those reviewed by the Clinical Pharmacogenetics Implementation Consortium (CPIC). Some emerging gene-drug information is included in the PSYQP test and clearly indicated as such in the report. Single gene test reports generally do not include medication recommendations due to the many diverse potential clinical applications. Our Pharmacogenomic Association Tables summarize information on many drugs and can be a useful tool, particularly for single gene tests or when the PSYQP test is ordered for a patient who will be prescribed a non-psychotropic medication.

Certain drugs might not be included due to limited clinical evidence. We encourage prescribers to contact us at 800-533-1710 with questions.

Why is enhanced formatting not used for my report?

Enhanced report formatting is not supported by some institutions. A copy of the enhanced report can be faxed upon request.

Which test should be ordered to evaluate for a specific drug?

Refer to our Pharmacogenomic Association Tables to determine which genes may be of interest for a specific drug. CAUTION: We do not report medications for which there is limited gene-drug information, including drug metabolism, response, and/or toxicity. Pharmacogenomic pharmacists are a great resource when considering patient care and dosing recommendations.

If questions remain regarding test selection for a specific drug, please call 800-533-1710 to speak with a genetic counselor or laboratory director.

What options are available for CYP2D6 gene testing?

  • The CYP2D6 gene is available as a single gene test (2D6Q) and is included in the PGXQP and PSYQP panel tests. If testing requires follow-up for CYP2D6, then reflex testing will be performed per our algorithm at an additional charge.
  • Tier 1 testing for CYP2D6 includes genotyping for specific variants and copy number analysis.
    • In approximately 3% of cases, Tier 1 testing results in ambiguous results and testing is reflexed to Tier 2 testing.
  • Tier 2 testing includes Sanger sequencing to define the CYP2D6 alleles present.   
    • Tier 2 testing can only be performed on blood specimens. Saliva specimens will not reflex to Tier 2 testing and therefore ambiguous results are possible.
    • Cascade testing can be avoided by sending in saliva because Tier 2 testing cannot be performed on saliva specimens.

Is blood or saliva the preferred specimen type?

  • We accept both blood and saliva samples for testing; however, due to lower DNA yield and quality, we highly recommend blood specimens, if possible.  
  • Saliva sample collection is useful in clinic settings that lack phlebotomy capabilities.
    • We only accept saliva specimens collected using an FDA-approved kit, which involves the patient using a specialized sponge to collect the saliva and then placing the sponge into a tube treated with preservative to prevent microbial growth. Mayo Clinic Laboratories clients can order approved saliva collection kits through a supply request: Saliva Swab Collection Kit (T786).
    • The patient must not eat, drink, smoke, or chew gum for 30 minutes prior to collection.
    • The samples are shipped as per usual to our laboratory, where the DNA is extracted.
    • Saliva samples are then processed in the same way as blood specimens.
  • Turnaround time for blood and saliva sample testing is similar, but due to the lower quality of saliva DNA, repeat testing is more common and may delay the result.

In instances where the patient has undergone a transplant, is blood or saliva preferred?

  • If the patient had a bone marrow transplant, we require a pre-transplant specimen or fibroblast culture for testing. Both blood and saliva will reflect the donor’s DNA and not be representative of the patient’s liver, where the bulk of the metabolism occurs.
  • In cases of liver transplant, please call 800-533-1710 to discuss specimen options with a genetic counselor or laboratory director.

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